In Thailand our 60 syndromes result from Alpha-thalassemia,Beta-thalassemia, Hb E and Hb Constant Spring genes and their interactions. This project proposes to study several aspects of these syndromes. Firstly, they are to be characterised by clinical, hematologic, pathologic and genetic studies. Biochemical analysis including globin synthesis and DNA mapping are to be performed. The problem of iron overload in thalassemia will be assessed by histopathologic study, chemical analysis of iron from organs, serum ferritin determination and measurement of plasma nontransferrin iron levels. Effects of agents capable of blocking intestinal iron absorption, and effects of newly developed effective oral iron chelating agents, will be investigated. Prospective study for infection problems in these patients matched with comparable controls will be carried out. The problems of pulmonary artery thromboembolism and hypoxemia in thalassemia will be investigated for underlying etiologies with emphasis on platelet function. Effects of certain therapeutic and preventive measures will also be investigated. Determinants for the great variability of severity in Beta-thalassemia/Hb E disease will be investigated by genetic study, biochemical analysis of the red cells and study of the reticuloendothelial function.